Fuel tank top off is bad. I'm now a believer.

whoa!!!

wow, you are really missing the point here. we aint talking fire hazards here. you need to reread this thread

 

Good info here. Thanks to OP for posting.

With the price of gas these days, you'd probably have to put $5 in to overfill! I just try to go up to the next dollar.

Gas prices are up again today. Glad I have my Prius!

 

I'd like to throw this into the mix regarding topping off the fuel tank and getting a full tank when filling up in the winter:

Today I filled the tank. It was -10Celcius (14F) and has been -30Celcius (-22F) at night here (Thunder Bay). I was careful not to top off, as I've read it can do damage to your fuel system. But the fuel indicator only went up to the second last bar (yes, I waited a long time for the indicator to rise -- its not rising above the second-last bar). i.e. the fuel indicator is not showing FULL even though the pump shut off when I was filling.

Is this the result of the collapsible bladder in the fuel tank?
How can I get a full tank of gas without jeopardizing the fuel system by topping off?

HDH

 

Never had that problem. Usually when I fill up, it may take about 10 to 20 seconds then my fuel gauge will start from the low position to the full position. Perhaps other members will chime in.

 

i always refill using the MFD mileage calculations and distance traveled. for example, if i am at 50 mpg and have gone 425 miles, i would not even consider stopping until i hit at least 8 to 8-¼ gallons

you can believe what you want, but fact is, your mileage stats on the MFD if you reset on every fillup is more than accurate enough to tell you how much gas to put in.

 

My problem is, regardless of my gas mileage (fuel economy), distance traveled, or gallons (Litres) occasionally when I fill up the tank it does not fill all the way. I know this because after a fill up the indicator only rises to the second-last bar. I'm motivated to top off to try and get the tank full, but Threads like this are clear about the dangers of doing that.

What the heckin' deck is going on??
Is there something wrong with the gas tank?
Is it just because of the cold weather?
because of the bladder?

Should I top off a little to get a full tank and risk fuel system damage, or just live with less then full tank at fill up?

FYI in the summer I can do 150-200km (93-124 miles) on the last fuel indicator bar that it's not currently filling to. :whoo:

...I love my prius, but I feel like I have a prius hangnail right now.

 

i be guessing that if the bladder is cold enough, it might not stretch fast enough as the gas comes in causing the initial click off. after the pump clicks off once, it has to reset itself before it will fill correctly, so if you are short a gallon or two and know it, you can probably wait a few seconds as the weight of the gas settles the bladder and then put more in it.

 

I think when it comes to the fuel tank on your vehicle, you have to learn what its particular quirks are and work with them. The way I read that description of the fuel system, the fuel gauge will indicate full when the bladder can't take any more gas (as opposed to the tank). So if you're filling in the cold, the pump clicks off, and you consistently only have 9 pips, you might be OK putting a little more in. Maybe not a whole gallon or two the first time, but maybe 1/4 to 1/2 gallon each time until you consistently show full after a fill.

And you probably need to be more careful depending on temperature. When I took the last road trip, it was about -10 and tried to fill up. It went up to full but dropped back down after ~5 miles. When I do a fill up usually around 20 F, it stays on full a little longer.

 

I think the most likely cause of your problem is that the gas station pump is not functioning well. It could be that the gas is flowing too fast or that the shut off is too sensitive. This may have nothing to do with your Prius. Try using another station and fill at the slowest rate possible. If this solves the problem, you have your answer.

 

Probably not. It happens at all the pumps I go to. And it happens winter or summer. At 1 bar flashing, all pumps shut off at about 8 to 8.5 gallons. Even if I KNOW I have used 10 or 10.5. So, yes I do 'top off' by pulling the nozzle out so I can get my 2 gallons, i.e. 100 miles. Yes those miles can be important with the local gas selling at $0.10 to $0.15 more per gallon than the stations on I/91. I can fill up there, do my weekly stuff and get back to the I/91 station on my weekly Monday run to MA.
But I'm not 'topping off' by filling until the gas is coming out the pipe.

There is this note in the Hybrid13.pdf file:

14F is a pretty regular temperature here in the winter. And I presume you don't get that 5 liter capacity back if the temp happens to be 15F. It has to be a more gradual.

It also says: Don't use premium gas, it may cause starting problems and there is no gas mileage benefit. I added this since there are somewhat frequent questions about using premium

 

70 degree temps today and I wanted to fill up at a 1/2 tank but the pump kept shutting off at about every 1/2 gallon.
Once I got to approx. 5 gallon, I quit. Tank registered full after startup.
It takes about 10-15 secs. for the gauge to register full.
Some of those pump handles have a habit of shutting off too early.eace:

 

I have always figured another reason overfilling is a bigger problem in the Prius is partly because the gasoline being pumped into the car is coming from an underground storage that is certainly at a cooler temperature then the temperature inside your fuel tank. In many cars / SUV's if you overfill you have already used 1/2 gallon or more just to travel 10 miles, giving the additional room in the tank as the gasoline gets warmer and expands. In the Prius you overfill and if you only travel 10 miles at most you have only used 1/4 of a gallon not leaving much if any room for temperature expansion.

 

You live in Ohio and think the ambient temperature is always higher than the underground tank temp? True in the summer but not in the winter!! At least not everywhere Underground temp is about 50F.

Your premise is correct in warmer weather. Fill it really full when it is 80F, then drive 1 mile home and park it and there is definitely potential for expansion problems.

 

Never really put much thought at all into it but what you said does make sense, and it would also explain the anomaly I've had with filling up when its cold outside. This winter my first PIP usually disappears rather quickly (20 Miles), sometime never even showing.

 

if only the tank was larger, I wouldn't feel the need to squeeze 12.5 gallons into my 11.6 gallon tank. Oh well, I'll keep doing it.

 

The pump never shut off today. Filled 3wk old mag grey prius at lowest setting and the gas kept going in. Stopped it myself when it was over 11gallons. Removed the gas pump and the gas came pouring out down the side of my car. Cleaned it up best I could but there was still gas in the area underneath my gas cap (bladder?).

Will check tomorrow morning to see if it is still there. Have I done permanent damage to my new toy?!

 

All this chatter and no answers?

Presuming one has either overfilled, literally gas at the top of the fill tube, and/or filled with the car ON, with or without the engine running, what's a body to do?

 

Re: All this chatter and no answers?

I'd suggest driving ~25 miles to lower the level 1/2 gallon. If you don't immediately park in the hot sun you should be OK.

 

Alright... problem resolved. After my prius puked up extra gas at me, it took
150 miles at avg 40mpg for the gauge to register any decrease in gas levels.
SCARY.

I've learned my lesson. never again.

btw
Since this incident I still havent had to fill the tank and i am pushing 400 miles on this tank- in NY- in the winter.

 

Ok - just had it happen to me 2 days ago. And I'm REALLY upset. The pump didn't shut off. I'm in NJ - one of the states (prob the only one) where you don't have to pump your own gas. Not paying attention I look and see 12+ gallons on the pump then hear it running out - snap off the seat belt - jump out of the car - grab the pump! And then here comes the attendant! ($38.02 later!!!) All this a 6am dressed for work! Manager gives me back $7.00 (whoopee). This is the one time I wasn't even empty empty since prices are going up so fast I figured this is my normal place the price was still "cheaper" - yeah right - ended up costing me more.
Anyhow - I've now driven over 200 miles and it JUST went down 1 tick mark. But the energy mpg is still saying I'm getting 52.3 or so.
So does this mean I'm ok? (please)
thanks